For years it seemed that American consumers' demand for liquid fuel was price inelastic-whether it was to drive their cars or get their brains going in the morning.

At first these went into safe, liquid assets like American Treasury bonds-the Asian financial crisis of 1997-98 was still a recent memory and many countries were keen to amass reserves.

As of 2007, the bottom 80 percent of American households held about 7% of the liquid financial assets.